Characteristics of Fungal Communities in Lava Plateau Ecosystems

Soil fungi are pivotal drivers of biogeochemical cycling, mediating nutrient transformation, plant-soil feedbacks, and ecosystem stability. Understanding their responses to vegetation succession is essential for predicting ecosystem recovery in fragile volcanic landscapes. We investigated soil fungal communities across five successional stages on the Jingpo Lake lava plateau-grassland (GL), shrubland (SL), deciduous broad-leaved forest (DB), coniferous and broad-leaved mixed forest (CB), and coniferous forest (CF)-using high-throughput ITS sequencing and soil physicochemical analysis. Basidiomycota and Ascomycota dominated at the phylum level, with Sebacina, Cortinarius, and Mortierella as core genera. Alpha diversity (Shannon, Simpson, Chao1) was significantly higher in early-successional GL and SL than in DB (p < 0.05), while CB exhibited the lowest community evenness (Pielou-e). Co-occurrence networks revealed greater connectivity in GL, whereas forest types showed simplified topologies. LEfSe identified distinct fungal biomarkers for each vegetation type. PICRUSt2-based functional prediction indicated biosynthesis as the dominant pathway (>40%), with significant variation among vegetation types. Redundancy analysis (RDA) identified soil organic matter (SOM) as the primary predictor of fungal community composition. Our findings indicate that vegetation succession is associated with changes in fungal diversity and function primarily linked to variations in SOM, with moisture regimes as a secondary contextual factor. Notably, advanced forest stages exhibited reduced fungal diversity and simplified community structure-highlighting a trade-off between nutrient enrichment and microbial complexity in volcanic ecosystems. These insights advance our understanding of plant-soil-microbe coupling during ecosystem restoration on lava plateaus.